Components having high heat flux densities, e.g. 60 W/mm2, are used today in computers. Heat from these components must first be transferred into a liquid circuit, and from there must be delivered via a liquid/air heat exchanger to the ambient air.
The discharge of heat from components having a high heat flux density is accomplished by means of so-called heat absorbers or cold plates. In these, heat is transferred to a cooling liquid, and the latter is usually caused to circulate, in forced fashion, in a closed circuit.
In this context, the cooling liquid flows through not only the heat absorber, but also a liquid pump that effects the forced circulation and brings about a suitable pressure buildup and volume flow through the heat absorber and an associated heat exchanger, so that the heat transfer coefficients pertinent to these heat exchangers become large, and the temperature gradients necessary for heat transfer become small.
A fan, which brings about forced convection of the cooling air on the air side of the heat exchanger as well as good transfer coefficients, is usually arranged on the heat exchanger.
Because of the limited space in most electronic devices, the pump and fan must be arranged in as space-saving a fashion as possible, i.e. a compact design is desirable.